I had exactly the same issue. Took me 2 nights to figure out so thought I should share how I got around it. I also tried all of those steps you mentioned above as well as many other things and had no luck. Here's what did work for me in the end:

Hey this is not a problem , this is just a step that you need to follow to update your database , your files has been updated successfully not the database , So when you hit this Url http://www.weeklyfun.nl/wp-admin/ you need to click "update WordPress database " just do this and you will be able to see your dashboard , but for safe side take your database backup in your locale system.

@jhaba That is how it "should" work. Unfortunately in this particular upgrade it would get stuck and not actually upgrade the database. All you would get is a blank screen and a continuous redirect to wp-admin/upgrade.php?_wp_http_referer=%2Fblog%2Fwp-admin%2F

Has never been a problem for me upgrading the wordpress files or the database before, but after googling around seems like many have had this same problem with the continuous white screen loop.

@jhaba For me there was no login screen, just a blank page. I could get the login screen by going direct to the wp-login.php file, however after logging in it would just divert to a blank page at wp-admin/upgrade.php?_wp_http_referer=%2Fblog%2Fwp-admin%2F

I have fixed my issue by using the steps outlined above so no need for me to reply any further. This topic should not be closed yet though as weeklyfun still needs to fix their site. My solution may or may not work for them, was just putting it out there in case it does.

I have uploaded 3.3.2., but still keep getting the message "Database Update required". I can not get into the admin anymore.
I have cleared my browsercache, and still it didn´t work. I don´t understand it.

Hi,
using an sql client access your database and check the wp_options table and check the siteurl row, make sure it has the correct info, also you can check wp_posts and wp_postmeta to make sure your content is safe.
There might be some server settings that won't allow php to change your database, it might have only content read+write rights and it might have no right over the "alter" command in mysql so contacting the hosting company wouldn't be a bad thing...
Regards

First check your tables for errors you might have a broken mysql database if that's not the thing ...
At that point what I would do if I were you would be to backup my database and site and reinstall the website without the database to see if you can make that work after that populate the database with the info you have now...

And then I went into my database and search at the table wp_options to db_version. It said it still was version 19470. I changed this to 21115 (latest version) and got back to my sites admin. It all worked fine now.